(a) Field of the Invention
The present invention relates to a softening agent composed of a particular silicone resin, emulsifier and antistatic agent, and to an industrial method of producing an acrylic fiber having animal hair-like touch by treatment with said softening agent.
(b) Description of the Prior Art
It is well known that knit fabrics produced from animal hair such as wool, cashmere, angora rabbit hair, etc. have excellent touch due to their particular slippery feel. In recent years, active attempts have been made to give such particular animal hair-like touch to synthetic fibers such as acrylic fibers.
For example, in Japanese Patent Publication No. 26436/69, a mixed treating agent of a slicone resin and an epoxy resin was disclosed as a treating agent for acrylic fiber products.
However, the touch of the final product becomes coarse by the stiffness due to the adhesion between fibers, and the slippery touch given by the silicon resin is hindered by the epoxy resin. Therefore the commodity value of the final product is materially reduced. On the other hand, the Applicant proposed in his Japanese Patent Publication No. 2556/76, method in which a particular silicone resin and an emulsifier selected from the group of POE (n') alkylphenyl phosphates are mixed under stirring with water to produce a weakly acid emulsion; the emulsion is applied to swollen gel acrylic filaments obtained by wet spinning; the filaments are dried immediately; and then a spinning oil is given to the filaments. By employing this method although it is possible to give slippery touch and softness resembling those of animal fiber products, and antishrinking properties to acrylic fibers or their products, this method necessiates two-step, two-bath treatment of the silicone treatment and oiling treatment, and therefore this method is not necessarily a desirable technique for industrial production. Thus, further improvements have been demanded.
Under such circumstances, we, the inventors, conducted research in various ways to provide a method of producing an acrylic fiber which will satisfy the touch and processability requirements at the same time by one-step treatment by the coexistence of an antistatic agent in a silicone emulsion. But when the antistatic agent was added to the silicone emulsion, the stability of the emulsion was remarkably impaired, and it was impossible to apply the treating agent uniformly to the fibers. Therefore, because of yarn breakage and winding around rollers caused in the succeeding steps, continuous operation was greatly hindered. Also, when a stable emulsion was obtained, it was impossible to produce fibers having satisfactory touch and processability. Thus, it was found that there was great difficulty in satisfying the touch and spinnability requirements at the same time.